1. Field of the Invention
The present invention relates to a passive wireless transponder.
2. Description of the Related Art
Radio frequency identification (RFID) tags are well known throughout industry, and are being increasingly utilized for supply chain management, inventory management, and logistic control. These tags can be written to and read from a handheld transceiver (referred to as an RFID reader) or fixed portal.
Small glass encapsulated low frequency RFID tags (see FIG. 1) are currently being utilized in surgical tools and implantable devices. These small “capsules” contain their own “onboard” antenna, which suffer extreme radio frequency degradation due to interference created by the proximity of the metals or liquids utilized in surgical tools implantable devices and surgical processes. As a result of this proximity, virtual contact (actual physical contact or less than ⅛ inch) must be made between the reader antenna and the surgical tool or implantable device in order to read or write to the RFID tag. This “virtual” contact requirement makes communication with a surgically implanted device impossible because of the distance associated with intervening soft tissues between the RFID reader and the implanted RFID tag.
Similarly, small RFID tags embedded or attached to surgical tools and implants may frequently be contained in a metal enclosure with small holes designed to allow the tools or implants to be sterilized using a high heat autoclave process. The metal enclosure prohibits the RFID tags located on or in the tools and implants to be read inside the enclosure. In order to read the tags inside the enclosure, the lid must be opened and virtual contact (actual physical contact or less than ⅛ inch) must be made between the reader antenna and the surgical tool or implant device in order to read the RFID tag. Again, this “virtual” contact requirement makes communication with a surgical implant or a full set of surgical tools within the enclosure impossible without removal of the contents of the enclosure.
What is needed in the art is an RFID transponder used with surgical instruments or implants that can be communicated with from a greater distance.